Vivariums house a number of animals, typically test animals, such as mice, in a number of cages, often a large number. The test animals are frequently used to test drugs, genetics, animal strains, husbandry practices, methods of treatment, procedures, diagnostics, and the like. We refer to all such uses of a vivarium as a study.
Regular weighing of animals is an important part of studies. In the prior art, weighing is done by hand and is labor intensive. The handling of the animals often changes their behavior or their health, altering the results or quality of the study. Also, handling the animals comprises the sterility of the cages and animals, putting the health of the animals and workers at risk.
Such manual weight recording is inherently infrequent due to the high labor time and cost. This infrequency creates three weakness of the prior art. First, problems may not be discovered until after an unacceptable delay, such as a failure to eat. Second, subtle behavior or health attributes, such as an animal's eating schedule, will be missed. Third, manual handling requires light for the worker. For many animals, this light interferes with and alters their behavior and health, and thus alters the results of the study compared with animals in their natural lighting regimen.
Vivarium cages are normally pathogen-free. Animals and thus their cages must be isolated from outside pathogens or contamination and from pathogens or contamination from other animals or other cages. This presents a significant challenge to vivarium automation and in particular to in-cage animal weighing and automatic animal identification. Electronic equipment placed inside a cage may need to be discarded after a single study due to the inability to sterilize the equipment between studies. Such equipment may be an animal ID sensor, a scale, or a wireless transmitter. In addition, in order to keep the cages pathogen-free it is desirable to have as few cage penetrations as possible. This means that power or data wiring to electronic equipment inside the cage is undesirable. Although this requirement motivates wireless devices, these devices must then be battery powered, which adds to cost, size and weight, and may introduce pathogens. Batteries may have to be changed out during a study, which adds to both equipment and labor costs and may introduce pathogens.
Sterility or pathogen free is important in vivariums to assure the health of the animals and the health of the workers. Also, sterility is critical for accurate, consistent, credible and repeatable study results. Sterility refers to the sufficient restriction of pathogen type and quantity so as to not affect the outcome of the study or the health or the behavior of animals or people. Sterility also refers to husbandry attributes, supplies and usage, as well as health.
An automated scale to meet vivarium requirements must have the following features: electronics in a fully sterile enclosure; animal chew-proof exterior; all components sterilizable by immersion in a sterilizing fluid; internal, rechargeable batteries; wireless connectivity, ideally redundant, ideally narrow range, ideally bi-directional; tool-less assembly and disassembly for sterilization and charging; free of clogging from bedding; reusable in different cages; free of dangerous or poisonous elements to animals; and a cage-mounting configuration to avoid movement by cage animals. Prior art with these features has not been identified.